<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8" />
  <title>electron demo</title>
  <style>
    html {
      margin: 0;
      height: 100%;
      width: 100%;
    }
    body {
      margin: 0;
      height: 100%;
      width: 100%;
    }
  </style>
</head>

<body>
  <div style="width:100%;height:100%;" id="root"></div>
</body>

</html>